This invention relates to the preparation of 1,3-propanediol. In one aspect, the invention relates to a cobalt-catalyzed process for manufacturing 1,3-propanediol in high yields without the use of a phosphine ligand for the cobalt catalyst.
1,3-propanediol (PDO) is an intermediate in the production of polyesters for fibers and films. It is known to prepare PDO in a two-step process involving (1) the cobalt-catalyzed hydroformylation (reaction with synthesis gas, H.sub.2 /CO) of ethylene oxide to intermediate 3-hydroxypropanal (HPA) and (2) subsequent hydrogenation of the HPA to PDO. The initial hydroformylation process can be carried out at temperatures greater than 100.degree. C. and at high syngas pressures to achieve practical reaction rates. The resulting product mixture is, however, rather unselective for HPA.
In an alternate synthesis method, the cobalt catalyst is used in combination with a phosphine ligand to prepare HPA with greater selectivity and at lower temperature and pressure. However, the use of a phosphine ligand adds to the cost of the catalyst and increases the complexity of catalyst recycle.
It would be desirable to prepare HPA in a low temperature, selective process which did not require the use of a phosphine ligand with the cobalt catalyst.
It is therefore an object of the invention to provide an economical process for the preparation of 1,3-propanediol which does not require the use of a phosphine-ligated catalyst for preparation of the HPA intermediate. It is a further object of one embodiment of the invention to provide a process for the preparation of 1,3-propanediol in which essentially all the cobalt hydroformylation catalyst can be conveniently recycled.